For shops doing a high volume of Switch Grip installation, the Reamer bit has 8 cutting edges ensuring optimum drill and fit for Outer Sleeve installation. Because the drill depth of Switch Grip is deeper than a traditional thumb solid and the dense core design in many high tech bowling balls, the 1 1/2 drill bit may drift at bottom of hole making the hole slightly off center. Keep in mind the Outer Sleeve is designed to be a press fit. The Outer Sleeve should never be installed with forced pressure. If the Outer Sleeve is forced into hole, the Inner Sleeve will not fit properly and will be very difficult to insert and remove. Reamer Bit 1 1/2" with stopper.